On a sunny day if a 36inch yardstick casts a 21inch shadow how tall is a building whose shadow is 168ft?

So, I can't give you the answer with the appropriate formulas or w/e but this is how I figure it out in my head

Find the ratio between the yard stick and it's shadow
36/21 = 1.71
This means that object creating the shadow is 171% taller that its shadow is long

Find the amount of inches in 168 feet (this is to be more accurate with your answer)

168 * 12 = 2016 inches

Multiply the previous number by the ratio found before

2016 * 1.71 = 3447.4 inches (or 287.3 feet)

If a 36 inch yardstick casts a 21 inch shadow, a building whose shadow is 168 feet is 287.3 feet tall

s'howyagottadoitboyyiie

Another answer:

Using trigonometry will give you a more accurate answer

Tangent ratio = opposite (the yardstick) divided by the adjacent (yardstick's shadow)

Tangent ratio = 36/21 = 12/7 in its lowest terms

Now rearrange the formula to find the height of the building

Tangent ratio*adjacent (the building's shadow) = opposite (the building)

12/7*168 = 288

The height of the building is 288 feet.